B/X cable Q

[Joe Wiliams]

I have a similar situation... installing a ceiling mounted heater.

It's a Dayton 240v - 5000 watt unit (20.9 amps) though can be wired for lower wattage. The manual recommends #10 awg wire and a 30 amp breaker.

I was planning on running NM wire from the breaker directly to the heater but I'm not sure how the transition from the attic through the ceiling is supposed to be (Sheetrock isn't installed yet but will be).

I'm pretty sure I can't just run the NM through the ceiling. What is the proper way to do this? Also, can I run #10 NM through 3/4" flexible metal conduit? There will about a 3' length from the ceiling to the heater. And can I attach the metal conduit connectors to a plastic gang box?

[Darius Ferlas]

I think there may be some confusion because of local naming schemes. Having read a lot on electrical on this (and other) forums I was told the correct name would be "armo(u)red cable" instead of BX. So this is how I referred to the product. My electrical inspector insisted on calling the cable BX though. So did a few major electrical distributors in Ontario so I call it BX henceforth.

I also learned that some Americans were surprised to see a BX with a ground wire so I'm posting a picture of the 3/3 I used for my subpanel. The cable has 3 insulated wires and a chunky ground one. The ground is of a lesser AWG than the other ones but still substantial and it connects to ground bars on both ends.

Relevant to this topic, these are some of things I was told by my inspector (Ontario) in regards to the BX cable:

1. You may not run a BX inside a conduit, except for very short runs such as through walls.
2. You may not strip the armour and run the resulting wires in a conduit, EMT or otherwise.

[Roger Frazee]

Use a metal box and I would splice to stranded wire inside the junction box. Get a 4 11/16" by 2 1/8" metal JB If splicing. Be sure to extend a ground wire pigtail to the box. In the back of the box will be a threaded hole to use a grounding screw (Green).

If you want to run continuous you can but it will be hard to make the bend unless you get a bigger junction box...these are common at an electrical supply not so common at the borg.

You will have a cover with a 3/4 center knockout. Then sides will also have 3/4 knockouts you will need on 3/4 cable clamp and locknut for the 10/2 with ground cable.

The 10/2G cable will have a black, white and bare. The black and white are your hots. It is code to mark the white.. permanently black.. (use a magic marker) for a few inches at the breaker and at the heater for identification as a hot wire. Bare of course is ground.

Sorta like this if you run continuous without splicing...

[Joe Wiliams]

Thanks Roger The only reason I was planning to run a continuous lines was the thought that the less connections the less potential problems. If this is of no real concern i'll go ahead and make a splice at the JB and then run stranded to the heater through the metal flex conduit. Unless there's a better way? I already have some 10/3 wire so I was going to use that unless there is an issue with having a 'spare' wire at each end.

Any tips on adding a remote thermostat? I haven't looked into that yet

[Roger Frazee]

Thanks Roger The only reason I was planning to run a continuous lines was the thought that the less connections the less potential problems. If this is of no real concern i'll go ahead and make a splice at the JB and then run stranded to the heater through the metal flex conduit. Unless there's a better way? I already have some 10/3 wire so I was going to use that unless there is an issue with having a 'spare' wire at each end.

Any tips on adding a remote thermostat? I haven't looked into that yet

For the 10/3 just cap the white wire. And use the red and black for hot.

Remote thermostat? Ok I think I see what your asking. The heater has a thermostat but it is up on the ceiling. I would wait and see what the instructions have to say about remote locations but I wouldn't think it would be hard to do.


Either way is fine. If you splice try to find ideal 'twister' wingnuts... these are IMO the best wingnut out there for connecting solid and stranded together. Let the stranded wire be about 1/8" to 3/16" past the solid when you place them into the cap.



Or you may prefer to use Wagos but be sure it is the Wago brand.. model 773-173..... the other brands don't cut the mustard. Watch the wire size range only the 773-173 will handle #10. Generally these are called wall nuts and will handle two wire sizes or three wire sizes or a combination. If you can find them I would use them.



Consider a premade stranded grounding pigtail for your connection to the box..one end will be stripped and one end will be a forked terminal or will have your 10-32 screw on a ring terminal either works well. Your ground connection will have 3 #10's this will be very stiff to handle for someone not used to it. I wouldn't lose any sleep if you use a #12 grounding pigtail....

[Matt Edwards]

Use a metal box and I would splice to stranded wire inside the junction box. Get a 4 11/16" by 2 1/8" metal JB If splicing. Be sure to extend a ground wire pigtail to the box. In the back of the box will be a threaded hole to use a grounding screw (Green).

If you want to run continuous you can but it will be hard to make the bend unless you get a bigger junction box...these are common at an electrical supply not so common at the borg.

You will have a cover with a 3/4 center knockout. Then sides will also have 3/4 knockouts you will need on 3/4 cable clamp and locknut for the 10/2 with ground cable.

The 10/2G cable will have a black, white and bare. The black and white are your hots. It is code to mark the white.. permanently black.. (use a magic marker) for a few inches at the breaker and at the heater for identification as a hot wire. Bare of course is ground.

Sorta like this if you run continuous without splicing...

Shouldnt there be a means of disconnect in there somewhere?

Matt

[Roger Frazee]

Yes there has to be a means of disconnect , but I would just let it be the circuit breaker. If Joe wants something more handy and closer to the heater then he could just install a pull out or other double pole disconnect.

[Joe Wiliams]

Thanks again Roger! You've been very helpful

You are correct about the thermostat, I would like to have it at 'user' level since I have 10' walls. The manual doesn't say anything about relocating the thermostat. It's not a big deal, just something I was thinking about.

Also, the actual distance from the breaker to the planned location of the heater is only about 6'.

[russell lusthaus]

As it turns out, I am wiring my circuit for the same heater.

10/3 armoured wire is what I have. I hear that it is not usually done, and may not be necessary, but is there any problem with running it inside EMT? Since it is already done, should I remove it?

Did I understand correctly that the thin Al bonding wire in my cables only function is to hold in the red head? And that I should just rely on the armored cable as the ground from breaker box to junction box?